Ophthalmic apparatus with corrective meridians having extended tolerance band by modifying refractive powers in uniform meridian distribution

ABSTRACT

The embodiments disclosed herein include improved toric lenses and other ophthalmic apparatuses (including, for example, contact lens, intraocular lenses (IOLs), and the like) and associated method for their design and use. The apparatus includes one or more optical zones, including an optical zone defined by a polynomial-based surface coincident at a plurality of meridians having distinct cylinder powers, wherein light incident to a given region of each of the plurality of meridians, and respective regions nearby, is directed to a given point of focus such that the regions nearby to the given region direct light to the given point of focus when the given meridian is rotationally offset from the given region, thereby establishing an extended band of operation, and wherein each of the plurality of meridians is uniformly arranged on the optical zone for a same given added power (in diopters) up to 1.0 D (diopters).

RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S. Provisional Appl. No. 62/312,321, filed Mar. 23, 2016 and U.S. Provisional Appl. No. 62/312,338, filed Mar. 23, 2016, each of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

This application is directed to lenses for correcting astigmatism, including providing increased tolerance for lens placement during implantation.

BACKGROUND

Ophthalmic lenses, such as spectacles, contact lenses and intraocular lenses, may be configured to provide both spherical and cylinder power. The cylinder power of a lens is used to correct the rotational asymmetric aberration of astigmatism of the cornea or eye, since astigmatism cannot be corrected by adjusting the spherical power of the lens alone. Lenses that are configured to correct astigmatism are commonly referred to as toric lenses. As used herein, a toric lens is characterized by a base spherical power (which may be positive, negative, or zero) and a cylinder power that is added to the base spherical power of the lens for correcting astigmatism of the eye.

Toric lenses typically have at least one surface that can be described by an asymmetric toric shape having two different curvature values in two orthogonal axes, wherein the toric lens is characterized by a “low power meridian” with a constant power equal to the base spherical power and an orthogonal “high power meridian” with a constant power equal to the base spherical power plus the cylinder power of the lens. Intraocular lenses, which are used to replace or supplement the natural lens of an eye, may also be configured to have a cylinder power for reducing or correcting astigmatism of the cornea or eye.

Existing toric lenses are designed to correct astigmatic effects by providing maximum cylindrical power that precisely matches the cylinder axis. Haptics are used to anchor an intraocular lens to maintain the lenses at a desired orientation once implanted in the eye. However, existing toric lenses themselves are not designed to account for misalignment of the lens that may occur during surgical implantation of the lens in the eye or to account for unintended post-surgical movement of the lens in the eye.

One type of toric lens design includes angularly-varying phase members that extend depth of focus features to extend the tolerance band of an intended correction meridian. However, lens design that extends the astigmatism tolerance of a toric IOL are not commonplace.

Accordingly, it would be desirable to have more intraocular lens designs that are tolerant to misalignments.

SUMMARY

The embodiments disclosed herein include improved toric lenses and other ophthalmic apparatuses (including, for example, contact lens, intraocular lenses (IOLs), and the like) and associated method for their design and use. In an aspect, an ophthalmic apparatus is disclosed having regions of one or more base spherical powers and one or more cylinder powers that are added to the one or more base spherical power for correcting an astigmatism (e.g., an intended astigmatism). The apparatus includes one or more optical zones, including an optical zone defined by a polynomial-based surface coincident at a plurality of meridians having distinct cylinder powers, wherein light incident to a given region of a given meridian of each of the plurality of meridians, and respective regions nearby, is directed to a given point of focus such that the regions nearby to the given region direct light to the given point of focus when the given meridian is rotationally offset from the given region, thereby establishing an extended band of operation, and wherein each of the plurality of meridians is uniformly arranged on the optical zone for a same given added power (in diopters) up to 1.0 D (diopters), here preferably each 0.5 D (diopters).

In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.01 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.05 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.1 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.15 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.2 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.25 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.3 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.35 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.4 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.45 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.5 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.55 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.6 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.65 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.7 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.75 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.8 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.85 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 0.95 D (diopters). In some embodiments, the meridians are uniformly arranged on the optical zones at about 1.0 D (diopters).

In some embodiments, differences among each continuously uniformly distributed contour line, at a given IOL plane, associated with a given meridian of the plurality of meridians is less than about 0.6 D (diopters).

In some embodiments, the polynomial-based surface establishes the extended band of operation across a range selected from the group consisting of about ±5 degrees, about ±6 degrees, about ±7 degrees, about ±8 degrees, about ±9 degrees, about ±10 degrees, about ±11 degrees, about ±12 degrees, about ±13, degrees, about ±14 degrees, and about ±15 degrees.

In some embodiments, the polynomial-based surface is characterized by a series of weighted cosine-based function.

In some embodiments, the plurality of meridians include a first meridian, a second meridian, and a third meridian, each having the extended band of operation of at least 10 degrees.

In some embodiments, a first center of the first meridian is angularly spaced about 90 degrees to a second center of the second meridian.

In some embodiments, the optical zone comprises a fourth meridian having an accumulated high surface amplitude such that the first meridian, the second meridian, and the third meridian have the established extended band of operation.

In some embodiments, the fourth meridian is purposely positioned at an angular position that coincides with a diagnosed limited retinal functional area of a patient.

In some embodiments, the polynomial-based surface comprises a refractive surface.

In some embodiments, the polynomial-based surface comprises a diffractive surface.

In some embodiments, an offset of each meridian of the plurality of meridians of about 10 degrees causes a MTF (modulation transfer function) measure change of less than 10% at 30 cycles per degree (cpd).

In some embodiments, the polynomial-bases surface at a first meridian and at a second meridian comprises a bifocal monofocal lens.

In some embodiments, the polynomial-bases surface at a first meridian comprises a monofocal lens.

In some embodiments, the polynomial-bases surface at a first meridian comprises an extended range lens.

In another aspect, a rotationally-tolerant ophthalmic apparatus is disclosed that is configured to correct astigmatism. The ophthalmic apparatus includes a multi-zonal lens body having a plurality of optical zones configured to apply cylinder power at an astigmatism meridian of an eye. The multi-zonal lens body forming a angularly-varying phase member having a peak cylinder power centered at an astigmatism correcting meridian, the angularly-varying phase member at the peak cylinder power being configured to direct light to a first point of focus on the retina, and the angularly-varying phase member varies, at each optical zone, along meridians nearby to the astigmatism correcting meridian to direct light to points of focus nearby to the first point of focus such the multi-zonal lens body, when rotational offset from the peak cylinder power, directs light from the nearby points of focus to the first point of focus, thereby establishing a band of operational meridians over the astigmatism meridian. The angularly-varying phase member has a profile that is uniformly spaced for every 0.5 D (diopters).

In some embodiments, the band of operation is established across a range selected from the group consisting of about ±5 degrees, about ±6 degrees, about ±7 degrees, about ±8 degrees, about ±9 degrees, about ±10 degrees, about ±11 degrees, about ±12 degrees, about ±13, degrees, about ±14 degrees, and about ±15 degrees.

In some embodiments, the polynomial-based surface is characterized by a series of weighted cosine-based function.

In some embodiments, the angularly-varying phase member has a band of operation of at least 10 degrees.

In some embodiments, the multi-zonal lens body forms a second angularly-varying phase member having a second peak cylinder power centered at a second correcting meridian, the second angularly-varying phase member at the second peak cylinder power being configured to direct light to a second point of focus on the retina. The second angularly-varying phase member varies, at each optical zone, along meridians nearby to the second correcting meridian to direct light to points of focus nearby to the second point of focus such the multi-zonal lens body, when rotational offset from the second peak cylinder power, directs light from the nearby points of focus to the second point of focus, and the second angularly-varying phase member has the profile that is uniformly spaced for every 0.5 D (diopters).

In some embodiments, the multi-zonal lens body forms a second angularly-varying phase member having a second peak cylinder power centered at a second correcting meridian, the second angularly-varying phase member at the second peak cylinder power being configured to direct light to a second point of focus on the retina. The second angularly-varying phase member varies, at each optical zone, along meridians nearby to the second correcting meridian to direct light to points of focus nearby to the second point of focus such the multi-zonal lens body, when rotational offset from the second peak cylinder power, directs light from the nearby points of focus to the second point of focus. The second angularly-varying phase member has a second profile that is uniformly spaced for every about 0.5 D (diopters).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention may be better understood from the following detailed description when read in conjunction with the accompanying drawings. Such embodiments, which are for illustrative purposes only, depict novel and non-obvious aspects of the invention. The drawings include the following figures:

FIG. 1 is a diagram of a polynomial surface that is uniformly arranged over a plurality of meridians that provides extended rotational tolerance, in accordance with an illustrative embodiment.

FIG. 2 is a diagram of the polynomial surface of FIG. 1 shown with the plurality of uniformly arranged meridians, in accordance with an illustrative embodiment.

FIG. 3 is a profile of the polynomial surface of FIG. 1 with the plurality of uniformly arranged meridians, in accordance with an illustrative embodiment.

FIG. 4 illustrates an example operation of the polynomial surface of FIG. 1 when subjected to misalignment, in accordance with an illustrative embodiment.

FIG. 5 is a schematic drawing of a top view of a human eye, in which the natural lens of the eye has been removed and replaced with an ophthalmic apparatus that includes an exemplified freeform-polynomial surface area, in accordance with an illustrative embodiment.

FIGS. 6A, 6B, 6C, and 6D are schematic diagrams of exemplary ophthalmic apparatuses that include either refractive or diffractive freeform-polynomial surfaces, in accordance with an illustrative embodiment.

FIGS. 7 and 8 include plots that illustrate the degraded performance of conventional toric lens when subjected to rotational misalignments.

FIG. 9 shows a combined cylinder map generated from the combination of the IOL cylindrical power (provided, in part, via the polynomial surface) combined with the corneal cylindrical power through meridians, in accordance with an illustrative embodiment.

FIG. 10 shows the combined cylinder map of FIG. 9 with the meridians shown in FIG. 2 superimposed thereon, in accordance with an illustrative embodiment.

FIGS. 11A and 11B each shows calculated MTF values as spatial frequencies of an exemplified IOL in a physiological eye model with astigmatic cornea in different cylindrical axis misalignment (CAM) situations between the cornea and the IOL for an iris pupil.

FIG. 12 is a surface SAG map of the polynomial surface of FIG. 1, in accordance with an illustrative embodiment.

FIG. 13 is diagram of a method to generate the polynomial surface of FIG. 1, in accordance with an illustrative embodiment.

FIG. 14 is a diagram of an example computing device configured to generate the polynomial surface disclosed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.

Embodiments of the present invention are generally directed to toric lenses or surface shapes, and/or related methods and systems for fabrication and use thereof. Toric lenses according to embodiments of the present disclosure find particular use in or on the eyes of human or animal subjects. Embodiments of the present disclosure are illustrated below with particular reference to intraocular lenses; however, other types of lenses fall within the scope of the present disclosure. Embodiments of the present disclosure provide improved ophthalmic lens (including, for example, contact lenses, and intraocular lenses, corneal lenses and the like) and include monofocal refractive lenses, monofocal diffractive lenses, bifocal refractive lenses, bifocal diffractive lenses, and multifocal refractive lenses, multifocal diffractive lenses.

As used herein, the term “refractive optical power” or “refractive power” means optical power produced by the refraction of light as it interacts with a surface, lens, or optic. As used herein, the term “diffractive optical power” or “diffractive power” means optical power resulting from the diffraction of light as it interacts with a surface, lens, or optic.

As used herein, the term “optical power” means the ability of a lens or optics, or portion thereof, to converge or diverge light to provide a focus (real or virtual), and is commonly specified in units of reciprocal meters (m−1) or Diopters (D). When used in reference to an intraocular lens, the term “optical power” means the optical power of the intraocular lens when disposed within a media having a refractive index of 1.336 (generally considered to be the refractive index of the aqueous and vitreous humors of the human eye), unless otherwise specified. Except where noted otherwise, the optical power of a lens or optic is from a reference plane associated with the lens or optic (e.g., a principal plane of an optic). As used herein, a cylinder power refers to the power required to correct for astigmatism resulting from imperfections of the cornea and/or surgically induced astigmatism.

As used herein, the terms “about” or “approximately”, when used in reference to a Diopter value of an optical power, mean within plus or minus 0.25 Diopter of the referenced optical power(s). As used herein, the terms “about” or “approximately”, when used in reference to a percentage (%), mean within plus or minus one percent (±1%). As used herein, the terms “about” or “approximately”, when used in reference to a linear dimension (e.g., length, width, thickness, distance, etc.) mean within plus or minus one percent (1%) of the value of the referenced linear dimension.

FIG. 1 is a diagram of cylindrical map of a polynomial surface 102 (also referred to as an ETA polynomial surface 102) that is uniformly arranged over a plurality of meridians that provides extended rotational tolerance, in accordance with an illustrative embodiment. The polynomial surface 102 is mapped to a surface of an ophthalmic apparatus 100 (not shown—see FIG. 6) to provide cylinder power to the ophthalmic apparatus, e.g., for the correction an astigmatism, or the like, such that the ophthalmic apparatus can be subjected to a cylindrical axis misalignment (CAM) (shown via arrow 104) of the meridian 106 a of up to 10 degrees without degradation of the corrective performance (e.g., with regard to visual acuity (VA) or modular transfer function (MTF)), as compared to when there no misalignment.

Notably, the polynomial surface 102 is uniformly arranged, in this embodiment, over a plurality of meridians 106 for every 0.5 D (diopters). It should be appreciated that other values can be used. In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.41 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.42 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.44 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.46 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.45 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.48 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.52 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.54 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.56 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.58 D (diopters). In some embodiments, the polynomial surface 102 is uniformly arranged over a plurality of meridians 106 for every 0.60 D (diopters). The number of the added power at which the meridian are uniformly distributed is set at an individual eye's tolerance of meridian power change such as the astigmatic or cylinder power. This value changes individually, up to 1.0 D (diopters), but on average a comfortable tolerance is about 0.5 D at the IOL plane.

FIG. 2 is a diagram of the ETA polynomial surface 102 of FIG. 1 shown with the plurality of uniformly arranged meridians 106 (shown as 106 a-106 ee), in accordance with an illustrative embodiment. As shown in FIG. 2 (and in FIG. 1), the ETA polynomial surface 102, in this example, includes three regions 202, 204, 206 (the center shown as 202 a, 204 a, and 206 a) of corrective cylindrical power—the first region 202 spanning between meridians 106 aa and 106 dd; the second region 204 spanning between meridians 106 d and 106 g; and the third region 206 spanning between meridians 106 k and 106 n. As shown, each of the meridians (106 a-106 q and 106 x-106 a) are uniformly arranged (i.e., uniformly spaced at various angular positions—here about 11 degrees apart) for every 0.5 D (diopters).

As shown in FIG. 2, meridian 106 a is located at about 90 degrees; meridian 106 b is located at about 79 degree; meridian 106 c is located at about 67 degree; meridian 106 d is located at about 55 degree; meridian 106 e is located at about 44 degree; meridian 106 f is located at about 33 degree; meridian 106 g is located at about 24 degree; meridian 106 h is located at about 11 degree; meridian 106 i is located at about 0 degree; meridian 106 j is located at about −12 degree; meridian 106 k is located at about −24 degree; meridian 106 l is located at about −36 degree; meridian 106 m is located at about −47 degree; meridian 106 n is located at about −56 degree; meridian 106 o is located at about −67 degree; meridian 106 p is located at about −79 degree; and meridian 106 q is located at about −90 degree; meridian 106 r is located at about −100 degree; meridian 106 s is located at about −112 degree; meridian 106 t is located at about −125 degree; meridian 106 u is located at about −135 degree; meridian 106 v is located at about −145 degree; meridian 106 w is located at about −158 degree; meridian 106 x is located at about −176 degree; meridian 106 y is located at about 168 degree; meridian 106 z is located at about 157 degree; meridian 106 aa is located at about 145 degree; meridian 106 bb is located at about 133 degree; meridian 106 cc is located at about 123 degree; meridian 106 dd is located at about 113 degree; and meridian 106 ee is located at about 101 degree.

It is contemplated that the ETA polynomial surface 102 may include more than three regions of corrective cylindrical power, e.g., a fourth region, a fifth region, and etc. In such embodiments, the regions between the corrective meridians may be uniformly reduced, e.g., to about 10 degrees apart, about 9 apart, about 8 degrees apart, about 7 degrees apart, and etc.

Table 1 illustrates examples of toric IOL designs with meridians uniformly distributed for a same added power, for a 0.25 D same added power, for a 0.5 D same added power, for a same 0.75 D same added power, and for a same 1.0 D same added power.

TABLE 1 Added Power Max Number of Max (in diopters) Added meridians (from number of between each Power low to low power corrective meridian (diopters) over ¼ of the lens) regions 0.25 D 4 D 16 (4/0.25) 6 0.5 D 4 D 8 (4/0.5) 3 0.75 D 4 D 5.3 (4/0.75) 3 1.0 D 4 D 4 (4/1) 3

As shown in Table 1, when the meridians are uniformly arranged for a same added power of 0.5 D, for a 4 D base, there are 8 meridians between the high power meridian and the low power meridian in a quadrant of the polynomial surface between meridian 106 a and 106 i. This allows for up to 3 corrective regions on the polynomial surface, as shown in FIG. 2. In another embodiment, when the meridians are uniformly arranged for a same added power of 0.75 D, for a 4 D base, there are 5.4 meridians between the high power meridian and the lower power. This allows up to 3 corrective regions of the polynomial surface. In another embodiment, when the meridians are uniformly arranged for a same added power of 0.25 D, for a 4 D base, there are 16 meridians between the high power meridian and the lower power. This allows up to 6 corrective regions of the polynomial surface. In another embodiment, when the meridians are uniformly arranged for a same added power of 1.0, for a 4 D base, there are 2 meridians between the high power meridian and the lower power. This allows up to 3 corrective regions of the polynomial surface, which has the high power meridian center located at meridians 106 e, 106 s, and 106 cc.

FIG. 3 is a profile 300 of the polynomial surface of FIG. 1 with the plurality of uniformly arranged meridians, in accordance with an illustrative embodiment. As shown in FIG. 3, each meridian (e.g., 106 b, 106 c, 106 d, 106 e, 1060 is defined by an angular position that is uniformly arranged, about 11 degrees apart, for every 0.5 D (diopters). In addition, the majority of meridian power change, from one meridian to the next, generates a change of more than 0.6 D power difference (shown as 304). The result is a profile 300 that is more uniformly sloped that provided extended range of operation beyond about 5 degrees of misalignment (e.g., up to 10 degrees misalignment), as compared to a conventional or macro regular cylindrical surface with power changes according to COS(2*theta) trend, for a given difference between two meridians, shown as profile 306. As shown in profile 306, the meridian distribution is not uniform. Specifically, the meridian (in degrees) from the minimum power meridian—namely 0 degrees (308 a)—is located at a 20.7-degree position (308 b), a 30-degree position (308 c), a 37.8-degree position (308 d), a 45.0-degree position (308 e), a 52.2-degree position (308 f), a 60-degree position (308 g), a 69.3-degree position (308 h), a 90.0-degree position (308 i), and etc., in a periodic trend, which provides a non-uniform meridian difference of about 20.7 degrees (between 308 a and 308 b), about 9.3 degrees (between 308 b and 308 c), about 7.8 degrees (between 308 c and 308 d), about 7.2 degrees (between 308 d and 308 e), about 7.2 degrees (between 308 e and 308 f), about 7.8 degree (between 308 f and 308 g), about 9.3 (between 308 g and 308 h), and about 20.7 degree (between 308 h and 308 i).

Referring still to FIG. 3, off-center structures of the polynomial surface 102 extend from the center structure in a gradually varying manner to apply cylinder power to a band of meridians surrounding the corrective meridian enabling the ophthalmic apparatus to operate off-axis (or off-meridian) to the corrective meridian (e.g., the astigmatism meridian). Notably, there are no more than 0.6-Diopter difference between any neighboring uniformly distributed contour lines.

In some embodiments, the polynomial surface 102 is defined by a combination of spline or polynomial (e.g., a Zernike polynomial, a Chebyshev polynomial, or a combination of both) that is constrained by the condition of the meridians being uniformly arranged apart for every 0.5 D (diopters).

FIG. 4 illustrates an example operation of the polynomial surface 102 of FIG. 1 when subjected to misalignment, in accordance with an illustrative embodiment. The polynomial surface 102, as a diffractive or refractive structure, in some embodiments, varies the extended depth of focus to a plurality of nearby focus points. To this end, light directed to such nearby focus points are thus directed to the desired focus point when the ophthalmic apparatus is subjected to a rotational offset from a primary intended axis of alignment, thereby extending the rotational tolerance of the apparatus to an extended tolerance band. In FIG. 4, a portion (402) of the polynomial surface 102 has a focus point 404 (e.g., referred to as a “main focus point” 404, e.g., to correct for an astigmatism) that is generated by a region about the center 406 of the portion 402 of the polynomial surface 102. In this example, a nearby region 408 of that portion 402 has a focus point 410 (e.g., referred to as an “auxiliary focus point” 410) that is offset from the main focus point 404. When the polynomial surface 102 is rotated about axis 412, e.g., as misalignment 106 is introduced to the corrective meridian Θ=0° (104), the focus point 410 of region 408 is moved towards the main focus point 404, thereby extending the band of operation of the polynomial surface 102. Remarkably, this extended tolerance astigmatism band delivers cylinder power to correct for the astigmatism for a range of meridians (e.g., up to ±10° as shown in FIG. 1, though can be more in other embodiments), thereby eliminating any need for additional corrective measures (e.g., supplemental corrective devices or another surgical intervention) when the implanted ophthalmic apparatus is not perfectly aligned to the desired astigmatism meridian in the eye.

Put another way, the polynomial surface 102 facilitates an extended band of the corrective meridian that has minimal, and/or clinically acceptable, degradation of the visual acuity and modulation transfer function when the ophthalmic apparatus is subjected to rotational misalignment between the astigmatic axis and a center axis of the corrective meridian.

FIG. 5 is a schematic drawing of a top view of a human eye 502, in which the natural lens of the eye 502 has been removed and replaced with an intraocular lens 100 (shown in simplified form in FIG. 6 and in greater detail in FIGS. 6A, 6B, 6C, and 6D). Light enters from the left of FIG. 5, and passes through the cornea 504, the anterior chamber 506, the iris 508, and enters the capsular bag 510. Prior to surgery, the natural lens occupies essentially the entire interior of the capsular bag 510. After surgery, the capsular bag 510 houses the intraocular lens 100, in addition to a fluid that occupies the remaining volume and equalizes the pressure in the eye.

After passing through the intraocular lens, light exits the posterior wall 512 of the capsular bag 510, passes through the posterior chamber 528, and strikes the retina 530, which detects the light and converts it to a signal transmitted through the optic nerve 532 to the brain. The intraocular lens 100 comprises an optic 524 and may include one or more haptics 526 that are attached to the optic 524 and may serve to center the optic 524 in the eye and/or couple the optic 5324 to the capsular bag 510 and/or zonular fibers 520 of the eye.

The optic 524 has an anterior surface 534 and a posterior surface 536, each having a particular shape that contributes to the refractive or diffractive properties of the lens. Either or both of these lens surfaces may optionally have an element made integral with or attached to the surfaces. FIGS. 6A, 6B, 6C, and 6D are schematic diagrams of exemplary ophthalmic apparatuses that include the freeform-polynomial surface area 102, in accordance with an illustrative embodiment. Specifically, FIGS. 6A and 6B show examples of diffractive lenses, and FIGS. 6C and 6D show examples of refractive lenses.

Referring still to FIG. 5, the intraocular lens 100 includes polynomial surface 102 (as a refractive, diffractive, or both) that focus at a plurality of focus points that are offset radially to one another so as to provide an extended tolerance to misalignments of the lens 100 when implanted into the eye 502. That is, when the center axis of a corrective meridian is exactly matched to the desired astigmatic axis, only a first portion of the cylinder axis is focused at the desired point of focus (338) (e.g., at the retina) while second portions of the cylinder axis focuses at other points (540) nearby that are radially offset to the desired point of focus (538). To this end, when the primary axis of the astigmatism of the intraocular lens is rotationally offset (shown as arrow 542) with the astigmatism of the eye, the second portion of the cylinder axis focuses the light to the desired point of focus.

Artificial lenses (e.g., contact lenses or artificial intraocular lenses) can correct for certain visual impairments such as an inability of the natural lens to focus at near, intermediate or far distances; and/or astigmatism. Intraocular toric lenses have the potential for correcting astigmatism while also correcting for other vision impairments such as cataract, presbyopia, etc. However, in some patients, implanted intraocular toric lenses may not adequately correct astigmatism due to rotational misalignment of the corrective meridian of the lenses with the astigmatic meridian. In some patients following the surgical implant of the toric lenses, the corrective meridian of the implanted toric lenses can be rotationally misaligned to the astigmatic meridian, in some instances, by as much as 10 degrees. However, toric lenses that are designed to provide maximum correction (e.g., 1 D to 9 D) at the astigmatic meridian are subject to significant reduction in effectiveness of the correction due to any misalignment from the corrective meridian. In certain designs, it is observed that if the cylindrical power axis were mismatched by 1 degree, there would be about 3 percent reduction of the effectiveness of the correction. The degradation increases with the degree of misalignment. If there were a 10-degree misalignment, there would be about 35% reduction of the effectiveness of the correction. This effect is illustrated in FIG. 7 discussed below.

FIGS. 7 and 8 include plots that illustrate the above-discussed degraded performance of conventional toric lens when subjected to rotational misalignments. This conventional toric lens is configured to provide 6.00 Diopters cylinder powers at the IOL plane, 4.11 Diopters cylinder power at the corneal plane, and a corneal astigmatism correction range (i.e., preoperative corneal astigmatism to predicted effects) between 4.00 and 4.75 Diopters.

Referring to FIG. 7, a plot of the undesired meridian power (also referred to as a residual meridian power (“OC”)) (shown along the y-axis) added due to the rotational misalignments (shown along the x-axis) of the toric IOL is shown, including the residual powers for i) a negative 10-degree misalignment (shown as line 702), ii) a 0-degree misalignment (shown as line 704), and iii) a positive 10-degree misalignment (shown as line 706). As shown, the undesired added meridian power varies between a maximum of ±0.75 Diopters at around the 45-degree meridian angle (shown as 708) and at about the 135-degree meridian angle (shown as 710). Notably, this undesired added meridian power is outside the tolerance of a healthy human eye, which can tolerant undesired effects up to about 0.4 Diopters (e.g., at the cornea plane) for normal visual acuity (i.e., “20/20 vision”). Because the undesired effects exceeds the astigmatism tolerance of the human eye, corrective prescription glasses, or further surgical operation to correct the implant misalignment, may be necessary to mitigate the effects of the misalignment of such toric IOLs.

This undesired meridian power, conventionally, may be expressed as Equation 1 below.

$\begin{matrix} {{OC} = {2\; \sin \; \alpha*\frac{c}{2}0.7\mspace{11mu} {\cos \left( {2\left( {\theta + 90 + \frac{\alpha}{2}} \right)} \right)}}} & \left( {{Equation}\mspace{14mu} 1} \right) \end{matrix}$

As shown in Equation 1, θ is the correction meridian (also referred to as the cylindrical power axis) (in degrees); C is the astigmatic power (at the IOL plane) to be corrected at meridian θ (in Diopters); and α is the magnitude of rotational misalignment of the cylindrical power axis to the astigmatic axis (in degrees).

FIG. 8 shows a plot illustrating the tolerance of a toric IOL to misalignment (shown in the y-axis) and a corresponding cylindrical power that may be applied (shown in the x-axis) for each misalignment to not exceed the astigmatism tolerance of the human eye (i.e., degrade the overall visual acuity). The tolerance to misalignment may be calculated as

${\alpha } \leq {\sin^{- 1}\frac{\frac{0.4}{2}}{\frac{c}{0.7}}}$

where α is the magnitude of rotational misalignment (in degrees). The calculation may be reduced to

${\alpha } \leq {\sin^{- 1}{\frac{0.29}{c}.}}$

As shown, for a misalignment of 5 degrees, which is routinely observed in IOL implantations, the correction effectiveness of such IOL implants can only be maintained for a toric IOL with 3.75 Diopters or less. That is, a toric IOL having cylinder power above 3.75 Diopters would exhibit degraded visual acuity due to the residual power exceeding the astigmatism tolerance of a human eye. This effect worsens with further degrees of misalignment. For example, at about 10 degrees, the effectiveness of a toric IOL is greatly reduced where only 1.5 Diopters cylinder power or less can be applied so as to not detrimentally affect the visual acuity. Given that cylinder power of convention toric IOLs may range between 1.00 Diopters and 9.00 Diopters, these toric IOLs are reduced in effectiveness post-operation due to the misalignments of cylinder axis.

Results of IOL with Exemplified Freeform-Polynomial Surfaces

FIG. 9 shows a combined cylinder map generated from the combination of the IOL cylindrical power (provided, in part, via the polynomial surface) combined with the corneal cylindrical power through meridians. FIG. 10 shows the combined cylinder map of FIG. 9 with the meridians shown in FIG. 2 superimposed thereon.

As discussed above with reference to FIG. 1, and as can be seen from the IOL cylinder map through meridians around the clock, there is remarkably no more than about 0.6 D difference for any continuous uniformly distributed contour lines at the IOL plane. The IOL SE is 20 D at the IOL plane. The IOL cylinder map of FIG. 1 is combined with the IOL SE to provide the overall IOL cylindrical map. That is, the astigmatism associated with test corneal cylindrical power has been attenuated and/or corrected for by the IOL cylindrical power provided, in part, by the polynomial surface.

FIGS. 11A and 11B each shows calculated MTF values as spatial frequencies of an exemplified IOL 100 in a physiological eye model with astigmatic cornea in different cylindrical axis misalignment (CAM) situations between the cornea and the IOL for an iris pupil. Notably, as shown in FIGS. 11A and 11B, the modulation transfer function (MTF) is maintained across the extended range of alignment for a lens configured with the freeform-polynomial surface area 102 of FIG. 1. Specifically, in FIGS. 11A and 11B, the MTFs for misalignment at 0 degrees, 5 degrees, and 10 degrees are shown (shown as “CAM=0 Deg” 1102, “CAM=5 Deg” 1104, and “CAM=10 Deg” 1106). In FIG. 11A, the iris pupil is about 3.0 mm. In FIG. 11B, the iris pupil is about 5.0 mm.

Notably, as can also be seen from the MTF curves, there are no cut-offs of the spatial frequency beyond 100 cpd (cycles per degree), which for an IOL with SE (Spherical Equivalent) of 20D (Diopters), this spatial frequency is approximately 30 cpd.

Corneal Irregular Geometry or Limited Retinal Area functions

In another aspect, the polynomial surface 102 of FIG. 1 is optimized to purposely place accumulated high surface amplitude (also referred to high order aberration) to non-functional retinal area so that the functional areas can fully benefit the ETA designs, that is, the enhanced image quality stability. Examples of non-functional retinal areas may include, but not limited to, areas of gradual loss of sight (e.g., associated with glaucoma or retinal macular degeneration (AMD).

Referring to FIG. 2, an accumulated high surface amplitude results at area 208 to provide enhanced image quality stability for the three corrective regions 202, 204, 206 that have uniform distributions discussed herein. In some embodiments, the corrective regions (e.g., 202, 204, 206) effectively span over a region greater than 90 degrees to angular extent. Confined by a finite surface region, it is contemplated that the accumulated (high) surface amplitude area 208 is purposely positioned (in a manner similar to the positioning of the corrective regions 202, 204, 206) to coincide, e.g., with areas of limited retinal functionality that may be present with a given patient. That is, the accumulated (high) surface area is specifically optimized optically to target the special optical needs of the entire eye on this area.

FIG. 12 is a surface SAG map of the polynomial surface 102 of FIG. 1, in accordance with an illustrative embodiment.

FIG. 13 is diagram of a method 1300 to generate, via a processor, the polynomial surface of FIG. 1, in accordance with an illustrative embodiment. As shown in FIG. 13, the method 1300 includes generating (1302), via a processor, an initial design (1304) comprising a base surface (with base cylindrical power) and sectional enhancements (with added cylindrical power in which each meridian is uniformly arranged for a same given added power) and iteratively generating (1308) and evaluating, a revised design (1310), generated according to an optimization routine (1308) that is performed based on sectional parameters, until pre-defined image quality metric values and boundary parameter are achieved. The sectional enhancements power of the initial design and the iterative design is the ETA polynomial surface of FIG. 1.

Referring still to FIG. 13, the method 1300 includes generating (1302) a first design (1304) via i) initial surface optical parameter, including a) base surface optical parameters 1312 and b) sectional surface optical parameters 1314, and ii) the pre-defined image quality metric values 1316. The base surface optical parameters 1312 include, in some embodiments, parameters associated with a radius of curvature for the toric lens (shown as “Radius of curvature” 1318), parameters associated with conic constant and aspheric coefficients (shown as “Conic constant” 1320), parameters associated with base cylinder power (shown as “Cylinder power” 1322), and parameters associated lens and/or coating material characteristics such as refractive index (shown as “Refractive index” 1324). Other parameters may be used as part of the base surface optical parameters 1312. The section surface optical parameters 1314, in some embodiments, includes parameters associated with sectional added power and meridian characteristics (shown as “Sectional add power” 1328) and parameters associated with high order aberration characteristics, e.g., Zernike aberrations above second-order (shown as “High order aberrations” 1328).

Referring still to FIG. 13, the parameters associated with the sectional added power 1326, in some embodiments, include a cylindrical power, for a given optical zone, for a same given added power in which meridians are uniformly arranged. In some embodiments, the cylindrical power for the added power are all refractive. The parameters associated with the high order aberration characteristics 1328, in some embodiments, include polynomial values (e.g., based on Zernike polynomials, Chebyshev polynomials, and combinations thereof) or characteristics such as polynomial orders and types as well as meridian boundaries for the high order aberrations. The high order aberration is constrained, e.g., from minimum to maximum cylindrical power over one or more meridian sections. In some embodiments, the high order aberrations is constrained or designated to a meridian, e.g., that corresponds to a corneal irregular geometry or limited retinal area functions. In such embodiments, the high order aberrations and its meridian locations on the lens surface may be optimized prior to the meridians for the uniform regions are determined to facilitate a customized design that is tailored for a given patient (i.e., particularly in view of corneal irregular geometry or limited retinal area functions). Such customization has a potential to truly benefit patients having cornea with or without astigmatism, patients with local Keratoconus with or without astigmatism, patients with glaucoma, patients with retinal macular degeneration (AMD), and the like.

Referring still to FIG. 13, the parameters associated with the pre-defined image quality metric value 1316 includes parameters associated with expected image quality metric (shown as “Expected image quality metric values” 1330) and parameters associated with special boundary restrain parameters (shown as “Special boundary restrain parameters” 1332). In some embodiments, image quality metric is based a comparison of a base polychromatic diffraction MTF (modular transfer function) (e.g., tangential and sagittal) to a number of error polychromatic diffraction MTFs values, e.g., where one or more polychromatic diffraction MTFs are determined for one or more misalignments of the generated toric lens from its intended operating meridians, e.g., at 5-degree misalignment and at 10-degree misalignment.

Referring still to FIG. 13, the initial design (1304) is evaluated (1334 a) to determine image quality metric values (e.g., the base polychromatic diffraction MTF, e.g., at 0 degree misalignment) and the error polychromatic diffraction MTFs, e.g., at the 5 and 10 degrees misalignment) and boundary parameters, e.g., as shown in FIGS. 11A and 11B. The determined image quality metric values are evaluated (1336) to determine whether the image quality metric values and boundary parameters meet an expected outcome, e.g., a value of 0.2. In some embodiments, the expected outcome is whether there is no cut off through spatial frequency beyond 100 cpd. Upon determining that the condition is met, the method 1300 is stop (1338). It is contemplated that other image quality metrics may be used, e.g., the optical transfer function (OTF), phase transfer function (PhTF), and etc.

Where the condition is not met, the method 1300 adjusts (1308) sectional parameters to be optimized and rerun the optimization to generate the revised design 1310. The adjusted sectional parameters may include meridians locations and meridian spacing among neighboring meridians. The optimization may include allowing the uniform contour lines to move from one meridian to a next meridian up based on an upper limit amount and a lower limit amount. As shown in FIG. 2, the uniform contour line 210 is show transitioning from meridian 106 m to meridian 106 n. The transition is constrained to occur along a specific radial position and without abrupt transition points.

Referring back to FIG. 13, the method 1300 then includes evaluating (1334 b) the revised design 1310 to determine image quality metric values (e.g., the base polychromatic diffraction MTF, e.g., at 0 degree misalignment) and the error polychromatic diffraction MTFs, e.g., at the 5 and 10 degrees misalignment) and boundary parameters, as discussed in relation to step 1334 a, and re-evaluating (1336) whether the revised image quality metric values and boundary parameters meet the expected outcome, as discussed in relation to step 1336.

In some embodiments, the method 1300 is performed in an optical and illumination design tool such as Zemax (Kirkland, Wash.). It is contemplated that the method 1300 can be performed in other simulation and/or design environment.

The present technology may be used, for example, in the Tecnis toric intraocular lens product line as manufactured by Abbott Medical Optics, Inc. (Santa Ana, Calif.).

It is not the intention to limit the disclosure to embodiments disclosed herein. Other embodiments may be used that are within the scope and spirit of the disclosure. In some embodiments, the above disclosed angularly varying phase members may be used for multifocal toric, extended range toric, and other categorized IOLs for extended tolerance of astigmatism caused by factors including the cylindrical axis misalignment. In addition, the above disclosed angularly varying phase members may be applied to spectacle, contact lens, corneal inlay, anterior chamber IOL, or any other visual device or system.

Exemplary Computer System

FIG. 14 is a diagram of an example computing device configured to generate the polynomial surface disclosed herein. As used herein, “computer” may include a plurality of computers. The computers may include one or more hardware components such as, for example, a processor 1421, a random access memory (RAM) module 1422, a read-only memory (ROM) module 1423, a storage 1424, a database 1425, one or more input/output (I/O) devices 1426, and an interface 1427. Alternatively and/or additionally, controller 1420 may include one or more software components such as, for example, a computer-readable medium including computer executable instructions for performing a method associated with the exemplary embodiments. It is contemplated that one or more of the hardware components listed above may be implemented using software. For example, storage 1424 may include a software partition associated with one or more other hardware components. It is understood that the components listed above are exemplary only and not intended to be limiting.

Processor 1421 may include one or more processors, each configured to execute instructions and process data to perform one or more functions associated with a computer for indexing images. Processor 1421 may be communicatively coupled to RAM 1422, ROM 1423, storage 1424, database 1425, I/O devices 1426, and interface 1427. Processor 1421 may be configured to execute sequences of computer program instructions to perform various processes. The computer program instructions may be loaded into RAM 1422 for execution by processor 1421. As used herein, processor refers to a physical hardware device that executes encoded instructions for performing functions on inputs and creating outputs.

RAM 1422 and ROM 1423 may each include one or more devices for storing information associated with operation of processor 1421. For example, ROM 1423 may include a memory device configured to access and store information associated with controller 1420, including information associated with IOL lenses and their parameters. RAM 1422 may include a memory device for storing data associated with one or more operations of processor 1421. For example, ROM 1423 may load instructions into RAM 1422 for execution by processor 1421.

Storage 1424 may include any type of mass storage device configured to store information that processor 1421 may need to perform processes consistent with the disclosed embodiments. For example, storage 1424 may include one or more magnetic and/or optical disk devices, such as hard drives, CD-ROMs, DVD-ROMs, or any other type of mass media device.

Database 1425 may include one or more software and/or hardware components that cooperate to store, organize, sort, filter, and/or arrange data used by controller 1420 and/or processor 1421. For example, database 1425 may store hardware and/or software configuration data associated with input-output hardware devices and controllers, as described herein. It is contemplated that database 1425 may store additional and/or different information than that listed above.

I/O devices 1426 may include one or more components configured to communicate information with a user associated with controller 1420. For example, I/O devices may include a console with an integrated keyboard and mouse to allow a user to maintain a database of images, update associations, and access digital content. I/O devices 1426 may also include a display including a graphical user interface (GUI) for outputting information on a monitor. I/O devices 1426 may also include peripheral devices such as, for example, a printer for printing information associated with controller 1420, a user-accessible disk drive (e.g., a USB port, a floppy, CD-ROM, or DVD-ROM drive, etc.) to allow a user to input data stored on a portable media device, a microphone, a speaker system, or any other suitable type of interface device.

Interface 1427 may include one or more components configured to transmit and receive data via a communication network, such as the Internet, a local area network, a workstation peer-to-peer network, a direct link network, a wireless network, or any other suitable communication platform. For example, interface 1427 may include one or more modulators, demodulators, multiplexers, demultiplexers, network communication devices, wireless devices, antennas, modems, and any other type of device configured to enable data communication via a communication network.

While the methods and systems have been described in connection with preferred embodiments and specific examples, it is not intended that the scope be limited to the particular embodiments set forth, as the embodiments herein are intended in all respects to be illustrative rather than restrictive.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification. 

What is claimed is:
 1. An ophthalmic apparatus having regions of one or more base spherical powers and one or more cylinder powers that are added to the one or more base spherical power for correcting an astigmatism (e.g., an intended astigmatism), the apparatus comprising one or more optical zones, including an optical zone defined by a polynomial-based surface coincident at a plurality of meridians having distinct cylinder powers, wherein light incident to a given region of a given meridian of each of the plurality of meridians, and respective regions nearby, is directed to a given point of focus such that the regions nearby to the given region direct light to the given point of focus when the given meridian is rotationally offset from the given region, thereby establishing an extended band of operation, and wherein each of the plurality of meridians is uniformly arranged on the optical zone for a same given added diopter of power up to 1.0 D.
 2. The ophthalmic apparatus of claim 1, wherein differences among each continuously uniformly distributed contour line, at a given IOL plane, associated with a given meridian of the plurality of meridians is less than about 0.6 D (diopters).
 3. The ophthalmic apparatus of claim 1, wherein the same given added diopter is about 0.5 D (diopters).
 4. The ophthalmic apparatus of claim 1, wherein the polynomial-based surface establishes the extended band of operation across a range selected from the group consisting of about ±5 degrees, about ±6 degrees, about ±7 degrees, about ±8 degrees, about ±9 degrees, about ±10 degrees, about ±11 degrees, about ±12 degrees, about ±13, degrees, about ±14 degrees, and about ±15 degrees.
 5. The ophthalmic apparatus of claim 1, wherein the polynomial-based surface is characterized by a series of weighted cosine-based functions.
 6. The ophthalmic apparatus of claim 1, wherein the plurality of meridians include a first meridian, a second meridian, and a third meridian, each having the extended band of operation of at least 10 degrees.
 7. The ophthalmic apparatus of claim 5, wherein a first center of the first meridian is angularly spaced about 90 degrees to a second center of the second meridian.
 8. The ophthalmic apparatus of claim 6, wherein the optical zone comprises a fourth meridian having an accumulated high surface amplitude such that the first meridian, the second meridian, and the third meridian have the established extended band of operation.
 9. The ophthalmic apparatus of claim 8, wherein the fourth meridian is purposely positioned at an angular position that coincides with a diagnosed limited retinal functional area of a patient.
 10. The ophthalmic apparatus of claim 1, wherein the polynomial-based surface comprises a refractive surface.
 11. The ophthalmic apparatus of claim 1, wherein the polynomial-based surface comprises a diffractive surface.
 12. The ophthalmic apparatus of claim 1, wherein an offset of each meridian of the plurality of meridians of about 10 degrees causes a MTF (modulation transfer function) measure change of less than 10% at 30 cycles per degree (cpd).
 13. The ophthalmic apparatus of claim 1, wherein the polynomial-bases surface at a first meridian and at a second meridian comprises a bifocal monofocal lens.
 14. The ophthalmic apparatus of claim 1, wherein the polynomial-bases surface at a first meridian comprises a monofocal lens.
 15. The ophthalmic apparatus of claim 1, wherein the polynomial-bases surface at a first meridian comprises an extended range lens.
 16. The ophthalmic apparatus of claim 1, comprising: an accumulated high surface amplitude area disposed at coordinates that coincides with non-functional or limited functional retinal regions of a given patient.
 17. A rotationally-tolerant ophthalmic apparatus for correcting astigmatism, the ophthalmic apparatus comprising a multi-zonal lens body having a plurality of optical zones configured to apply cylinder power at an astigmatism meridian of an eye, the multi-zonal lens body forming a angularly-varying phase member having a peak cylinder power centered at an astigmatism correcting meridian, the angularly-varying phase member at the peak cylinder power being configured to direct light to a first point of focus on the retina, and wherein the angularly-varying phase member varies, at each optical zone, along meridians nearby to the astigmatism correcting meridian to direct light to points of focus nearby to the first point of focus such the multi-zonal lens body, when rotational offset from the peak cylinder power, directs light from the nearby points of focus to the first point of focus, thereby establishing a band of operational meridians over the astigmatism meridian, and wherein the angularly-varying phase member has a profile that is uniformly spaced for every 0.5 D (diopters).
 18. The apparatus of claim 17, wherein the band of operation is established across a range selected from the group consisting of about ±5 degrees, about ±6 degrees, about ±7 degrees, about ±8 degrees, about ±9 degrees, about ±10 degrees, about ±11 degrees, about ±12 degrees, about ±13, degrees, about ±14 degrees, and about ±15 degrees.
 19. The apparatus of claim 17, wherein the polynomial-based surface is characterized by a series of weighted cosine-based function.
 20. The apparatus of claim 17, wherein the angularly-varying phase member has a band of operation of at least 10 degrees.
 21. The apparatus of claim 17, wherein the multi-zonal lens body forms a second angularly-varying phase member having a second peak cylinder power centered at a second correcting meridian, the second angularly-varying phase member at the second peak cylinder power being configured to direct light to a second point of focus on the retina, and wherein the second angularly-varying phase member varies, at each optical zone, along meridians nearby to the second correcting meridian to direct light to points of focus nearby to the second point of focus such the multi-zonal lens body, when rotational offset from the second peak cylinder power, directs light from the nearby points of focus to the second point of focus, and wherein the second angularly-varying phase member has the profile that is uniformly spaced for every 0.5 D (diopters).
 22. The apparatus of claim 17, wherein the multi-zonal lens body forms a second angularly-varying phase member having a second peak cylinder power centered at a second correcting meridian, the second angularly-varying phase member at the second peak cylinder power being configured to direct light to a second point of focus on the retina, and wherein the second angularly-varying phase member varies, at each optical zone, along meridians nearby to the second correcting meridian to direct light to points of focus nearby to the second point of focus such the multi-zonal lens body, when rotational offset from the second peak cylinder power, directs light from the nearby points of focus to the second point of focus, and wherein the second angularly-varying phase member has a second profile that is uniformly spaced for a same given added diopter of power up to 1.0 D. 